A disclaimer first: Until now, I have never lived in an authoritarian regime.
My thoughts are educated guesses at best. However, there may be some behaviour rules that will help the country until the tyrant is gone, regardless of the reason he goes.
I think it is a safe assumption that all of his and his minions' actions are evil and will harm real people. Since he thinks like a tyrant, then all his actions are directed to his own benefit regardless of any harm that may hurt citizens. This is the root definition of evil: a lack of empathy. He considers other people to be objects without feelings or worth who can be manipulated and/or destroyed for his personal benefit.
Some of us want to prevent the tyrant from inflicting harm on the country with any of his programs and initiatives. We may be in a position to impede his and his minions' machinations. We should do so wherever we can.
My basic mind set is that whatever he chooses to do will be harmful for the general population while any benefits accrue to him and his cronies.
Here's an idea of how to impede and delay his evil programs for those in positions of power: continue to vocally support the tyrant while at the same time you are obstructing any and all actions he wishes you to perform. "Of course I support you because you are mighty and wise, I am only sorry that I was not able to do what you asked. I will try harder."
If the tyrant says that he will fire you for poor performance, then make him do just that, don't do his job by quitting. Continue deflecting and offering excuses as long as you can since that will use up his attention and delay other harms he wants to do.
That is disgusting behaviour for anyone. However, it is justified since that behaviour is exactly what the tyrant does every day.
When all the directions from the tyrant will harm the people you love and he has political violence at his disposal, it will likely be foolish of you who are in a power position to 'get in his face' and call him out. That time has passed for any minor action. Of course, there may be something so bad that you are willing to torpedo your career to stop him; if so, the God bless you.
Others may be unable to sabotage his programs because they are outside positions of power; those of us in that position should march, protest and strike with as much vigour as we can find. Some political scientists suggest that tyrannies fall when 3.5 % of the population demonstrates continuously against the regime. Recent protests have seen 5 million people march and demonstrate; that number has been growing. 3.5% of the population is about 11 million, so we must continue to protest.